Models of Brane Cosmology
One of the earliest documented attempts on brane cosmology is dated by 1983. The authors discussed the possibility that the Universe has dimensions, but ordinary particles are confined in a potential well which is narrow along spatial directions and flat along three others, and proposed a particular five-dimensional model.
In 1998/99 Merab Gogberashvili published on Arxiv a number of articles where he showed that if the Universe is considered as a thin shell (a mathematical synonym for "brane") expanding in 5-dimensional space then there is a possibility to obtain one scale for particle theory corresponding to the 5-dimensional cosmological constant and Universe thickness, and thus to solve the hierarchy problem. It was also shown that four-dimensionality of the Universe is the result of stability requirement since the extra component of the Einstein field equations giving the confined solution for matter fields coincides with the one of the conditions of stability.
In 1999 there were proposed the closely related Randall-Sundrum (RS1 and RS2; see 5 dimensional warped geometry theory for a nontechnical explanation of RS1) scenarios. These particular models of brane cosmology have attracted a considerable amount of attention.
Later, the pre-big bang, ekpyrotic and cyclic proposals appeared. The ekpyrotic theory hypothesizes that the origin of the observable universe occurred when two parallel branes collided.
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